Conventional throttle bodies are operated mechanically and employ a position sensor mounted to a valve shaft to sense the position of a throttle valve. While generally adequate, there is risk of inaccurate reading of the position by a mis-calibrated sensor. However, with emissions and fuel economy standards on the rise, allowing for these potential inaccuracies in sensor calibration is becoming more of a concern.
Further, in order to allow for additional flexibility and precision in operation of the throttle body assemblies, some vehicle manufacturers are considering the use of electronically controlled throttle bodies, which are not mechanically linked to the accelerator pedal. Some examples of electronic controls are stepper motor controlled throttle valve movement, stepper motor idle control and purely electronic throttle control. In these cases, accuracy of the electronic control in positioning the throttle valve is important, creating even more concerns with the potential for initial calibration inaccuracies.
Thus, a means for better testing for initial calibration of throttle bodies is becoming more important. Current testing and calibration techniques are cumbersome and expensive. Conventional techniques for production testing of throttle plate positioning include, among others, either integral, throttle body mounted, potentiometer type sensors, or external position sensors such as inductive pickup encoders that require the throttle to be partially disassembled so that the sensor can be temporarily attached to the throttle plate shaft. This partial disassembly for production testing of throttle plate positioning is a time consuming task that limits throughput of throttle bodies under the calibration test procedures.
Therefore, a quick and inexpensive system is needed that will accurately measure the calibration of production throttle bodies.